From ec376a2ab97ec3be52ca282dc6ac102e805d1005 Mon Sep 17 00:00:00 2001 From: Dirk Brandewie Date: Thu, 4 Apr 2013 10:35:35 -0700 Subject: [PATCH 1/2] cpufreq / intel_pstate: Set timer timeout correctly The current calculation of the delay time is wrong and a cut and paste error from a previous experimental driver. This can result in the timeout being set to jiffies + 1 which setup the driver to race with itself if the APIC timer interrupt happens at just the right time. References: https://bugzilla.redhat.com/show_bug.cgi?id=920289 Reported-by: Adam Williamson Reported-and-tested-by: Parag Warudkar Signed-off-by: Dirk Brandewie Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index ad72922919ed..6133ef5cf671 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -502,7 +502,6 @@ static inline void intel_pstate_set_sample_time(struct cpudata *cpu) sample_time = cpu->pstate_policy->sample_rate_ms; delay = msecs_to_jiffies(sample_time); - delay -= jiffies % delay; mod_timer_pinned(&cpu->timer, jiffies + delay); } From 6f389a8f1dd22a24f3d9afc2812b30d639e94625 Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Sun, 7 Apr 2013 02:14:14 +0000 Subject: [PATCH 2/2] PM / reboot: call syscore_shutdown() after disable_nonboot_cpus() As commit 40dc166c (PM / Core: Introduce struct syscore_ops for core subsystems PM) say, syscore_ops operations should be carried with one CPU on-line and interrupts disabled. However, after commit f96972f2d (kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()), syscore_shutdown() is called before disable_nonboot_cpus(), so break the rules. We have a MIPS machine with a 8259A PIC, and there is an external timer (HPET) linked at 8259A. Since 8259A has been shutdown too early (by syscore_shutdown()), disable_nonboot_cpus() runs without timer interrupt, so it hangs and reboot fails. This patch call syscore_shutdown() a little later (after disable_nonboot_cpus()) to avoid reboot failure, this is the same way as poweroff does. For consistency, add disable_nonboot_cpus() to kernel_halt(). Signed-off-by: Huacai Chen Cc: Signed-off-by: Rafael J. Wysocki --- kernel/sys.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/sys.c b/kernel/sys.c index 39c9c4a2949f..0da73cf73e60 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -324,7 +324,6 @@ void kernel_restart_prepare(char *cmd) system_state = SYSTEM_RESTART; usermodehelper_disable(); device_shutdown(); - syscore_shutdown(); } /** @@ -370,6 +369,7 @@ void kernel_restart(char *cmd) { kernel_restart_prepare(cmd); disable_nonboot_cpus(); + syscore_shutdown(); if (!cmd) printk(KERN_EMERG "Restarting system.\n"); else @@ -395,6 +395,7 @@ static void kernel_shutdown_prepare(enum system_states state) void kernel_halt(void) { kernel_shutdown_prepare(SYSTEM_HALT); + disable_nonboot_cpus(); syscore_shutdown(); printk(KERN_EMERG "System halted.\n"); kmsg_dump(KMSG_DUMP_HALT);